The invention lies in the automotive technology and engineering fields. More specifically, the invention relates to a method of controlling an electromechanical actuating drive for a gas exchange valve of an internal combustion engine.
A prior art internal combustion engine (see German utility model DE 296 07 963 U1) has at least one gas inlet valve and at least one gas outlet valve for each cylinder. The valves are driven by an electromechanical actuating drive. Particularly the gas outlet valve must open counter to a high cylinder internal pressure as a function of the current load state of the internal combustion engine. For this purpose, therefore, high opening forces must be applied as a function of the current load state. In the known internal combustion engine, the gas outlet valves are each provided on their side facing away from the cylinder interior, at a distance from the valve head, with a piston disk which is guided in a pressure compensating space. The pressure compensating space is capable of being connected to the cylinder interior via a pressure compensating duct. The piston disk can thus be acted upon in the opening direction of the gas outlet valve by the cylinder internal pressure. The disturbing forces occurring as a result of the cylinder internal pressure and acting on the gas outlet valve are therefore largely eliminated. In the prior art internal combustion engine, complicated bores have to be provided in the engine block and the cylinder head, and the gas inlet and gas outlet valves are designed differently, with the result that they can be produced in each case only in small quantities.
The object of the present invention is to provide a method for controlling an electromechanical actuating drive for a gas exchange valve of an internal combustion engine which overcomes the above-noted deficiencies and disadvantages of the prior art devices and methods of this general kind, and which is simple and which ensures that the electromechanical actuating drive operates reliably.
With the above and other objects in view there is provided, in accordance with the invention, a method for controlling an electromechanical actuating drive for a gas exchange valve of an internal combustion engine, which comprises:
calculating an estimated value for a disturbing force resulting from gas forces acting on a gas exchange valve immediately prior to opening the gas exchange valve;
estimating a time profile of the disturbing force resulting at the gas exchange valve after a commencement of opening from a response of a transfer member modeling the time profile of the disturbing force, to a jump in the disturbing force from the estimated value to a predetermined value, wherein an output variable of the transfer member represents the disturbing force; and
determining an actuating signal for the actuating drive as a function of the time profile of the disturbing force; and
controlling the electromechanical actuating drive with the actuating signal.
In accordance with an additional feature of the invention, the gas exchange valve is an outlet valve.
In accordance with an added feature of the invention, the estimated value of the disturbing force is calculated as a function of a variable characterizing the commencement of opening of the outlet valve and of a variable characterizing an air mass prior to combustion in a cylinder of the internal combustion engine.
In accordance with another feature of the invention, the estimated value of the disturbing force is calculated as a function of a fuel/air ratio.
It is also possible, according to a further feature of the invention, to calculate the estimated value of the disturbing force as a function of an ignition angle.
In accordance with yet a further feature of the invention, the estimated value of the disturbing force is calculated as a function of a variable characterizing an exhaust-gas pressure in an exhaust-gas tract of the internal combustion engine prior to the commencement of the opening of the outlet valve.
In accordance with again an added feature of the invention, at least one parameter of the actuating member is determined as a function of at least one operating variable of the internal combustion engine. Such exemplary operating variables include the rotational speed and/or a variable characterizing the commencement of the opening of the outlet valve.
In accordance with a concomitant feature of the invention, the above-noted transfer member is a PT1 member.
The invention is distinguished in that the electromechanical actuating drive can be operated with a low power loss and yet reliable operation of the actuating drive is ensured, irrespective of the disturbing force which acts on the gas exchange valve and which occurs as a result of the gas forces acting on the latter. The profile of the disturbing force is estimated accurately with a very high time resolution. It is therefore necessary to have only a small actuating reserve of the actuating forces which must be applied by the electromechanical actuating drive.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for controlling an electromechanical actuating drive for a gas exchange valve of an internal combustion engine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.